Electric motors and generators are used in a variety of applications. One such application is in small electric motors which are commonly utilized in engine cooling fan modules (ECF modules). In general, a typical motor includes field windings that surround a centrally located shaft, which is rotatable mounted in the ECF motor. A commutator is mounted on the motor shaft and placed in electrical contact with a power supply by two or more brushes spaced about the commutator and in contact with the commutator.
Traditionally, motor components have been supported on a skeletal frame made of metal to provide adequate support. Recently, non-metal molded motor frames and housings have been incorporated in an attempt to reduce the weight of the motor. Even in such light weight applications, the commutator brushes must be supported within the motor frame. In some designs, metal brush guides or brush boxes are attached to a plastic base, and the metal boxes support the brushes. Metal brush boxes are effective heat conductors and, as such, can help to cool the brushes. The metal brush boxes, however, exhibit undesired deformation during assembly operations, and add excessive weight.
In other designs, plastic brush guides are incorporated. While effectively reducing the weight of the motor, plastic is significantly less effective at removing heat from the brushes. The reduced cooling ability lessens the efficiency of the motor. Additionally, because of structural concerns when using plastic as opposed to metal, the electrical shunt which connects the brush to other electrical components in a device is routed through an upper wall of the plastic brush guide. This horizontal extension adds to the overall height requirements of the motor which can be problematic for ECF motor applications.
Accordingly, there is a need for a plastic brush guide which allows for improved heat conduction away from brushes housed therein. An ECF module that incorporates a brush guide which does not unduly increase the horizontal height of the motor portion of the ECF module would be further beneficial.